Could not find module `@ember/-internals/routing/lib/system/route` imported from `ember-custom-elements/route-connections`

[kevinkucharczyk]

I tried using this addon in a brand new Ember app at the latest LTS, version 4.12.3.

Unfortunately it doesn't work, with the following error:

Uncaught Error: Could not find module `@ember/-internals/routing/lib/system/route` imported from `ember-custom-elements/route-connections`
    at missingModule (loader.js:247:1)
    at findModule (loader.js:258:1)
    at Module.findDeps (loader.js:168:1)
    at findModule (loader.js:262:1)
    at requireModule (loader.js:24:1)
    at Object.r [as require] (loader.js:176:1)
    at Module.callback (route-connections.js:31:1)
    at Module.exports (loader.js:106:1)
    at Module._reify (loader.js:143:1)
    at Module.reify (loader.js:130:1)